Open Heavens is an encounter with God, when humanity meets divinity. It is the intervention of Heavens on Earth, the duplication of heaven on earth.
... Thy kingdom come. Thy will be done, as in heaven, so in earth.
It is a sign of God's Blessings, a reward of obedience, a sign of God's presence. Isaiah 64:1
Distinctive features of Open Heaven
Dimensions of Open Heaven
However, to make a reality an Open Heaven, then obedience is needed. Deuteronomy 28: 1-4, prayers is required as well as tithes and offering Malachi 3:10